This invention relates to a contouring tool for grinding cylindrical worm profiles, in turn used to grind gear wheels.
Several processes are known for profiling cylindrical grinding worms, which are used to grind the teeth on usually predressed and hardened gear wheels.
A quite accurate, but slow and time-consuming process constitutes generating the contour of the worm by means of shaped diamonds that are ground. The diamonds are used in the same manner as turning tools, and the procedure for this type of contouring can be compared with the cutting of a thread with a lathe. Since this process is slow and since the shaped diamond tools are very sensitive and uneconomical, this process is rarely used today.
Another possibility is called the crushing process in which a crusher roll without its own drive is forced against the slowly turning grinding worm with great force. In this manner the dulled grains are dislodged from the disk matrix and the contour of the worm gradually assumes the shape of the contour of the crusher roll. This process has the advantage that such contoured shapes as crown and root reliefs can be produced without any great difficulties. However, one drawback is the relatively rapid wear of the crusher roll during contouring, and the very large forces that occur during the crushing procedure.
Similarly, the contouring roll has also been known for a long time. Such a roll has a layer of grains made of a hard substance, and its outer diameter is shaped to match the contour of the grinding worm. In contrast with the crusher roll, it is driven at a high speed with a motor, and the contour of the worm is produced by means of a cutting process with relatively little energy. The drawback of this process is that the very high accuracy, which must be demanded of the contouring roll, can hardly be attained. It is impossible to coat the foundation of the roll with grains of a hard substance having the requisite quality.
Simple, conical profiling disks are also known that are coated with hard material grains. However, with these contouring disks only the flank portions of the grinding worms can be contoured. These contouring disks can be lapped and thus achieve high precision. Such contouring disks are usually used in pairs, one for the left and one for the right flank profile of a disk. The drawback of the contouring disks that are most commonly used today is that the crest and/or root radii of the grinding worm profile cannot be contoured at the same time in the course of the operation, thus making the automation of the contouring process more complicated.